Leaf Scorching following Foliar Fertilization of Wheat with Urea or Urea–Ammonium Nitrate Is Caused by Ammonium Toxicity

Foliar fertilization is a potential tool to increase the use-efficiency of nitrogen (N) fertilizers. However, whilst leaf scorching has frequently been reported, the underlying physiological processes are not clear. In the present work, we investigate the intensity of leaf scorching as affected by t...

Full description

Saved in:
Bibliographic Details
Published inAgronomy (Basel) Vol. 12; no. 6; p. 1405
Main Authors Castro, Saulo Augusto Quassi de, Kichey, Thomas, Persson, Daniel Pergament, Schjoerring, Jan Kofod
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.06.2022
Subjects
Accumulation
Agricultural production
amino acid
Ammonium
ammonium concentration
Ammonium nitrate
Assimilation
Biodiesel fuels
Biofuels
Experiments
Fertilization
Fertilizers
Glutamate-ammonia ligase
Glutamine
glutamine synthetase
Grain
Leaves
Nitrates
Nitrogen
nitrogen fertilizer management
Plant growth
Proteins
Substrates
Surfactants
Toxicity
Urea
Online AccessGet full text

Cover

More Information
Summary:Foliar fertilization is a potential tool to increase the use-efficiency of nitrogen (N) fertilizers. However, whilst leaf scorching has frequently been reported, the underlying physiological processes are not clear. In the present work, we investigate the intensity of leaf scorching as affected by the balance between ammonium assimilation and accumulation. Leaves were sprayed with urea–ammonium nitrate (UAN) solution without surfactant or applied liquid droplets of urea in different N concentrations with surfactant. UAN solutions without surfactant containing >10% N caused leaf scorching already after 24 h and the severity increased with the N concentration. The same pattern was observed 3 days after the application of urea solutions containing >4% N together with surfactant. The scorching was accompanied by a massive increase in foliar and apoplastic ammonium (NH4+) concentration. Moreover, the activity of glutamine synthetase (GS), most pronouncedly that of the chloroplastic isoform (GS2), decreased a few hours after the application of high N-concentrations. Along with this, the concentration of glutamate—the substrate for GS—decreased. We conclude that leaf scorching is promoted by NH4+ accumulation due to a limitation in N assimilation capacity.
ISSN:2073-4395
2073-4395
DOI:10.3390/agronomy12061405